Update RAC example in readme for RAC 2.0.

- The RACAble macro has been replaced with the RACObserve macro in RAC 2.0.
Merge pull request #1 from rastersize/patch-1

Update RAC example in readme for RAC 2.0.
Add color animations to -[UIView backgroundColor].
Allow IFTTTAnimation subclasses to use initWithView.
Merge pull request #3 from IFTTT/color_animations

Color Animations
added factory methods to various objects
added variadic methods for creating keyframes
Merge pull request #5 from jeremyflores/factory_variadic_methods

Factory & Variadic Methods
Merge pull request #1 from IFTTT/master

Update fork